Thermionic valve circuits



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?atented Aug. 2, 1927.

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THERMIONIC VALVE CIRCUITS.

Application tiled October 27, 1926, Serial No. 144,553, and in Great Britain July 2, 1925.

This invention relates to thermionic valve4 therefore it has been the usual practice to avoid such electromagnetic coupling hy arranging; the said inductances in noninductive relationship. This is not always convenient however. For example the known methods of screening' .the inductances or orientating them in a specific manner may he inconvenientfrom the point of view of design. Furthermore `it may be desirable to determine the orientation of the inductances in accordance with other considerations, as for exemple the elimination of electromagnetic coupling between remoteelements of an amplifier..

ln accordance with the present invention the inductances are located in mutually inductive relationship and means are provided for neutralizing for a considerable range of wave length the electrornotive force induced in either circuit by the other as a result of the said mutually inductive relationship.

The said means comprise means for ninipressing an electromotive force on either circuit as a result ofthe current iiowingin the other. which electromotive force is of such a value as to neutralize the said electroinotive force induced as a result of said mutually inductive relationship. l

An embodiment of the invention will now he described with reference to the accompanying drawing.l which is a diagrammatic illustration of the relevant part of a valve circuit system in accordance with the invention.

ln the arrangement shown two auxiliary inductances a1 and c2 are connected together in a closed circuit and are. respectively located in inductive relationship with the inductance 1 and L2. The values, directions oi windings etc. are so selected that J I am aware' that it is common practice to f provide means for neutralizing the capacity coupling between 'two oscillatory circuits associated with e thermionic valve. Said means however can operate to neutralize the magnetic coupling` between said circuits for one specific wave length only.

I am also aware that it has been proposed in valve circuits having tuned anode and.

grid circuits to connect en inductance in series in the anode circuit, which inductance is coupled to the grid circuit-in such a sense as to produce a. reversed reaction' elle-ct. i In my opinion however this arrangement produces e damping edect upon the grid circuit and not s. magnetic neutralizingI eect.

What l" claim and -desire to secure by Letters )Patent isz-- A thermionic valve system comprising a valve having grid, filament and plate elec-u trodes, .an input circuit disposed between said grid and filament electrodes, an output circuit included between said plateand {ilament electrodes, independent inductances for tuning each of said circuits, an'auxiliary circuit including separate inductance elements in series, one of said elements being coupled to one of said aforementioned inductances and the other of said elements being coupled to the other of said aforementioned independent inductances, and a connection from said auxiliary circuit to said filament electrode` said inductances beingv related for neutralizing for a considerable range of wave length the electromotive torce induced in either of said input or out- .put circuits by mutual inductive relationship 'of said independent inductances. In witness whereof I aflix my signature.

PETER. WILLAM WLLANS. 

